1. Field of the Invention
The present invention relates to a bluetooth wireless technology, and particularly, to a method for direct voice telephone call between bluetooth terminals.
2. Background of the Related Art
Bluetooth is a technology for connecting a portable device which can be connected to from all over the world and a network device with a size of 9 mm×9 mm as 100 MW. The bluetooth technology is a radio standard of short wave length depending on a radio link (2.4 GHs Information System Management Open Band) within 10 m to 100 m range, and concentrates on a communication between internet devices. The bluetooth technology partitions frequency bands to transmit data, and transmits frequency to the partitioned frequency bands as dividing the frequency. The bluetooth is also used for moving data from one channel to the other channel utilizing the above spectrum.
Further, the bluetooth technology is able to bind eight devices in a network with a piconet. The bluetooth technology can be applied to various devices such as voice transmission or the Internet because it supports all synchronous/asynchronous applications.
The network of the bluetooth (topology) can be constructed as a point-to-point network, or a point-to-multipoints network, any unit of a piconet can be connected to the other piconet to construct a scatternet. The core of the bluetooth application is to make interface of a digital apparatus wireless. There are various applications based on the bluetooth technology. Presently, applications using the bluetooth technology are cellular phone application, wireless headset, and three-in-one phone.
The cellular phone application is basically an application of the bluetooth technology and takes the advantage of the bluetooth technology. Specifically, the cellular phone application can be performed using an audio channel, which is the biggest advantage of the bluetooth technology. In addition, the wireless headset is the first application in the early stage of the implementation of bluetooth technology. A user is able to speak on the phone using the wireless headset when the cellular phone is in a bag or in a pocket, and the wireless headset can be used as a hands free device while the user drives a car. Further, the three-in-one phone is a phone system capable of performing three functions when the bluetooth technology is installed on one cellular phone. The cellular phone in which the bluetooth technology is installed can be used as a wireless phone which is connected to a wired phone in a house, it can also be used as an intercom or a walkie-talkie talking to a person within a close range.
FIG. 1 is a diagram showing a standard protocol stack of the bluetooth technology. The protocol stack comprises a service discovery protocol (SDP), a connection-less (CL), a connection-oriented (CO), a logical link control and adaptation layer protocol (L2CAP), a link management protocol (LMP), a synchronous connection-oriented (SCO), and an asynchronous connection-less (ACL).
A terminal including the bluetooth protocol stack, as shown in FIG. 1, uses the CL and CO in a cordless telephone profile, and also uses CO in an intercom profile as a signaling path. In addition, the terminal synchronizes audio data through the SCO connection. A telephony control specification (TCS)-binary comprises a call control (CC), a connection-less (CL) TCS, group management (GM) and protocol discrimination modules.
A cordless telephone profile among the TCS—binary based profiles of the bluetooth uses the CL TCS and the CO as the signal path, and synchronizes audio data through an SCO connection. The TCS—binary based profile comprises a call control (CC), the CL TCS, the GM, and the protocol discrimination modules (not shown). The LMP is a link management protocol layer, SDP is a service discovery protocol layer, and L2CAP is the logical link control and adaptation layer protocol layer in FIG. 1.
In addition, there are some call status states of the voice communication when it is made by the above bluetooth protocol stack such as a null, an active, a disconnect request, a disconnect indication. The call status further includes a release request, a call initiated, an overlap sending, an outgoing call processing, a call present, a call received, a connect request, and an overlap receiving states.
Call setting and releasing the set call processes in a bluetooth terminal including the above bluetooth protocol stack are shown in FIG. 1. These two call status states will be described as follows with reference to FIGS. 2A and 2B.
FIG. 2A is a flow chart showing a call setting process in the bluetooth terminal including the bluetooth protocol stack shown in FIG. 1. An outgoing terminal transmits a setup message to an incoming terminal in order to set a call (step S11). The incoming terminal which received the setup message transmits a setup acknowledge message to the outgoing terminal (step S12).
The outgoing terminal which received the setup acknowledge message transmits information needed to set the call to the incoming terminal (step S13). There are more than one kind of information which is needed to set the call. When the information is transmitted to the incoming terminal, the incoming terminal and the outgoing terminal generate a signal and an alarming sound for call setting. Subsequently, the incoming terminal which transmits the alarming sound to the outgoing terminal transmits a connecting message to the outgoing terminal (step S14˜step S16). The outgoing terminal which received the connecting message transmits a connecting acknowledge message to the incoming terminal (step S17). When the connecting acknowledge message is transmitted to the outgoing terminal, the call setting process is completed.
FIG. 2B is a flow chart showing a process for releasing the set call in the bluetooth terminal including the bluetooth protocol stack shown in FIG. 1. The outgoing terminal transmits a call disconnecting message to the incoming terminal (step S21). The incoming terminal which received the call disconnecting message transmits a call releasing message to the outgoing terminal, and the outgoing terminal after received the call releasing message transmits a call releasing complete message to the incoming terminal finally (step S22˜step S23).
However, in the general bluetooth protocol stack described above, the bluetooth is for embodying the service using various applications. Therefore, the structure of the bluetooth is complex to perform only the voice communication. Further, the vocoder standard for voice communication and the vocoder standard used by a wireless mobile communication terminal, which supports the bluetooth are different from each other. Thus, resources are wasted when a mobile communication terminal, which is capable of direct voice communication by the bluetooth is embodied, and complexity and redundancy are increased.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.